Geniorsbyran h



Patented fiept. 9, 1924,

Uhllfl GENIORSBYRAN I-I.

METHOD OF No Drawing.

T 0 all whom it may concern:

Be it known that I, Anonns HoLMBERG, a citizen of the Kingdom of Sweden,residing at Stockholm, Sweden, have invented new and useful Methods ofSintering Fine Ores and the like, of which the following is aspecification.

This invention relates to an improved method of sintering fine ores andthe like.

It is well-known to sinter fine ores and the like in such manner thatthe ore is intimately and uniformly mixed with pulverulent fuel and themixture charged in flat pans whereupon the charge is ignited at theupper surface and the fuel combusted by a downwardly induced current ofair. In operating in such manner the ore in the lowermost layers of thecharge is generally heated to a higher temperature and is more stronglysintered than in the uppermost layers on account of the fact that theformer part of the charge is heated not only by the combustion of thefuel mixed therewith but also by heat which is conveyed by thecombustion gases from the upper layers. This circumstance is aconsiderable draw-back especially in treating hard-sintered ores whichrequire a high percentage of fuel for securing igniting and sintering ofthe surface layer, in as much as the high percentage of fuel easilycauses smelting and partial reduction of the ore in the undermost layerswhich makes the ore unsuitable for further treatment.

The object of the present invention is to avoid said draw-back andsimultaneously to save fuel in sintering fine ores in sintering pans.The invention consists, chiefly, in charging the sintering pan withlayers of ore containing different percentages of fuel in such mannerthat the percentage of fuel gradually decreases from the top to thebottom of the sintering apparatus, and then G. TORULF, OF STOCKHOLM,

SWEDEN.

SIN'IERING FINE OR'ES AND THE LIKE-.

Application filed. January 22, 1923. Serial No. 614,292.'

igniting the charge on the upper surface and combusting the fuel by adownwardly induced current'of air. By said manner of distributing thefuel in the charge a very good and uniform sintering efiect is obtained.The number. of layers containing different percentages of fuel may betwo or more.

When sintering fine iron ores in a flat sintering pan having a depth of300 m. m. for instance 6% by weight of finely ground cokes must be addedto the ore when the fuel is uniformly mixed with the ore. According tomy invention I can obtain a better and more uniform sinter for instanceby charging the pan with an undermost layer of 100 m. m. thicknesscontaining 1% coke only, then a second layer of 150 m. m. thicknesscontaining 5% coke, and uppermost a layer of m. m. thickness containing7% coke. Such charge is easily ignited at the upper surface and thecombustion of the fuel by a downwardly induced current of air causes auniform heating of the whole charge resulting in a very good sinter.Moreover on third of the fuel is saved in comparison with the abovementioned example with an ore that is uniformly mixed with fuel in thewhole charge.

What I claim is:

Method'of sintering fine ores in sintering pans, consisting in chargingthe sintering pan with layers of ore containing percentages of fuel insuch manner that the fuel gradually decreases from the top to thebottom, igniting the charge at the upper surface and combusting the fuelby a downwardly induced current of air.

In testimony whereof I have signed my name.

ANDERS HOLMBERG.

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